DENVER (AP) -- John Lackey was originally going to throw an inning simply to stay sharp.
That plan was changed to a full-fledged start, to keep in rhythm.
Only, this wasn't exactly the outing he was looking for with the postseason drawing near.
Lackey allowed three solo homers, including one to Charlie Blackmon, the first batter he faced, as the Boston Red Sox fell to the Colorado Rockies 8-3 on Tuesday night.
''Not our best night from the mound,'' manager John Farrell said. ''I thought John made a couple of mistakes that he had to pay for, particularly in a ball park where you put the ball in the air and it's going to carry.''
Even more, Lackey (10-13) struggled on the road again, allowing four runs and six hits in six innings. The right-hander is 1-5 away from Fenway Park since the All-Star break.
Lackey also surrendered solo homers to Troy Tulowitzki and Corey Dickerson.
Not that he's too concerned with this performance.
''I'm good to go,'' Lackey said. ''Feel good.''
Tyler Chatwood (8-5) shut down a potent Red Sox lineup as he gave up one unearned run and three hits before being pulled for a pinch hitter with a 4-1 lead in the seventh.
The Rockies went on to score four times that inning to seal the win, with DJ LeMahieu and Michael Cuddyer delivering two-run singles.
Cuddyer finished the night 2 for 4 with a double to raise his average to an NL-best .335.
For the Rockies, this was a confidence-inducing victory.
''For sure. Boston is a great team, going into the playoffs,'' Dickerson said. ''You want to play well, show our resilience as a team and to play hard to the last game.''
With the AL East title wrapped up, the Red Sox are now focused on securing the best record in the league. They maintain a one-game lead over Oakland after the Athletics lost 3-0 to the Los Angeles Angels.
Farrell is using these last few games as a way figure out his final postseason roster spots. Farrell said there are a couple still up for grabs.
David Ortiz played first base instead of Mike Napoli without the use of a designated hitter. Ortiz showed off his glove, too, snaring a scorching liner from Dickerson to end the sixth.
Chatwood pitched carefully to the dangerous Ortiz, even intentionally walking him in first with a runner on second. The ploy worked as Jarrod Saltalamacchia grounded out.
Later, Ortiz hit a fly to the deepest part of the park, but Blackmon tracked it down.
The only mistake Chatwood made wasn't on the mound but covering first base in the seventh. With two outs and Will Middlebrooks on second, Todd Helton made a diving stop on Jackie Bradley Jr.'s grounder and quickly flipped it to Chatwood, who dropped the ball before stepping on the base.
Chatwood scooped it up and threw wide to home plate and into the Red Sox dugout, allowing Middlebrooks to score. Chatwood was charged with two errors on the play and Bradley advanced to third.
But Chatwood escaped more damage when his wild pitch bounced off the wall behind home plate, allowing catcher Jordan Pacheco to quickly field the ball and flick it to Chatwood, who tagged out Bradley, keeping the score 4-1.
''That lineup is really tough,'' Chatwood said. ''You've got to execute every pitch.''
Blackmon, the reigning NL player of the week, began the game with a homer to right on a fastball from Lackey. Cuddyer soon followed with a double and scored on Helton's single.
Helton clapped his hands after his hit as the crowd roared. The first baseman will retire at the end of the season after 17 years with the Rockies.
Before the game, Helton said he didn't ''do nostalgia'' and didn't want to reflect back on his career just yet. He holds virtually every hitting category in Rockies history and will play his final home game Wednesday night.
Helton nearly was a member of the Red Sox had a rumored trade before the 2007 season taken place. That was the season the Red Sox went on to sweep the Rockies to capture the World Series title.
Asked how close he was to being in a Boston uniform, Helton said: ''I have no idea. You have to talk to the people that were making the decisions.''
NOTES: Saltalamacchia hit a two-run homer in the ninth after Ortiz singled. ... Red Sox OF Jacoby Ellsbury (right foot) may return to the lineup as soon as Wednesday. ... Rockies owner Dick Monfort is pleased with the performance of first-year manager Walt Weiss and hopes he returns. Monfort said the sides have yet to talk about a new deal.